Stencil sheet and method of preparing coating therefor



Patented May 13, 1930 i PAUL A. GOLLNICK AND NAOMI GOLLNICK, MESNE ASSIGNMENTS, TO SELECTOGRAPH PORTION OF ILLINOIS STENCIL SHEET AND METHOD OF PREPARING COATING THEREFOR No Drawing.

This invention relates to stencils and particularly to stencil sheets comprising a tibrous, porous support, such as Japanese yoshino paper, having a hardened coating of organic colloid, impervious to ink, in which the stencil characters are cut, by the expression process, to permit the ink or other coloring to print through the fibers of the paper or other porous support.

One of the common types of stencils long in use consisted of Japanese yoshino paper coated with gelatin which was coagulated either by a chrome salt such dichromate, or by an aluminum salt, which chemically combined with the gelatin to form a hard coating. 1 v I In order to adapt the coated sheet for making the stencil by pressure, as for instance by the impact of the types of a typewriter, the sheet must be dampened so as to permit the type to rupture the impervious film without cutting or otherwise injuring the fiber of the paper, or other porous support. In dampening coated'sheets which have been hardened by aluminum salts. alone, the fibers of the paper have a tendency to stretch so as to cause the stencil to become baggy in the frame, and the paper has a tendency to become sticky. For this reason, aluminum salts have not been satisfactory as hardening agents.

Potassium dichromate as a hardening agent is also objectionable because it necessitates two steps in the coating process. When potassium dichromate is employed, the stencil sheet must first be coated with the glue or gelatin. and then coated with the hardening solution. If the potassium dichromate were mixed with the glue or gelatin, before being applied to the sheet, coagulation would take place in the. solution, thereby rendering it difficult to appl The main ob ects of this invention are to provide an improved coating material which is water proof and which has none of the aforementioned objectionable characteristics inherent in solutions containing chrome or aluminum salts; to provide a coating solution which may be applied in one o eration; to provide an improved water proo coating for stencil sheets which will toughen the sheets Application filed September 12, 1928. Serial No. 305,609.

as potassium.

or CHICAGO, ILLINOIS, ASSIGNORS, BY COMPANY, or CHICAGO, ILLINOIS, A conand prevent them from becoming baggy after being dampened; and to provide an improved proress ofpreparmg a water proofv coating material of this kind.

Stencils may be made of any suitable fibrous porous material, but Japanese yoshino paper is preferred because of its thin texture.

The improved coating material comprises a mixture of a colloid, a volatile vehicle, a vegetable drying oil, a tempering agent, and a metallic dryer.

The colloid is the base or binding agent. It binds together the fibers of the paper and gives strength to the sheet A good grade of hide glue has been found to be satisfactory and is cheaper than gelatin.

The vegetable drying oil is the water-proofing agent. Linseed oil has been found highly satisfactory for this purpose. When mixed with the colloid it forms an emulsion. If desired, the linseed oil may be replaced by Chinawood oil, soya bean oil, or by a mixture of these oils.

The volatile. vehicle may be water or any other suitable solvent which evaporates quickly after the film has been applied. to the sheet.

Glycerine is preferred as the tempering agent, but it may be replaced by such materials as diethylphthalate, monacetin, triace- U tin, etc. The stencil sheet, after being coated with the improved mixture, is kept in a flexible condition by the tempering agent which retains enough moisture to keep the sheet from becoming brittle.

In order to hasten the drying of the film applied to the sheet, the coating preferably contains a metallic. dryer. Lithargeis satisfactory, but it may be replaced by any of the common dryers such as resinates, oleates and palmitates of aluminum, cobalt, copper, lead, manganese and zinc.

The aforementioned ingredients may be combined in varied proportions, but it has been found that highly satisfactory results can be obtained as follows:

Two pounds of. glue or gelatin are soaked in two quarts of cold water for four hours or more. It is then heated to degrees centigrade'and twelve ounces of linseed oil, containing two per cent, by weight, of litharge, added, and the mixture is then stirred until thoroughly emulsified.

While the mixture is being stirred, and the temperature of C. maintained, two and one-half pounds of glycerine are added. The emulsion is then thinned down to the proper consistency by the addition of hot water. This usually requircsabout two gallons.

When the it iperature of the mixture has dropped to or 0 (1, the coating material is ready for application. The sheet may coated in any suitable manner, as, for in ance, la the floating process, by a sprayer with a b 4- l-Illol ly (l. will i istood that the product and the rariow the prom, s may be modified by omi sion or alteration of details and substitution of ingredients, without departing from the swirit or the invention as defined by the folio "mg claims Ye claim 1. The process of preparing a material for coating stencil sheets which consists in mix ing an animal colloid and Water, heating the mixture to about 70 centigrade, adding linseed oil to the heated mixture, stirring the mixture, and then adding glycerine.

2. The process of preparing a material for coating stencil sheets which consists in soaking glue in Water, heating the glue and water to 70 0., adding linseed oil and litharge, stirring the mixture until emulsified, adding glycerine, and then adding hot Water.

3. A stencil sheet'carrying a coating including an uncoagulated colloidal protein in admixture with a vegetable drying oil, a tempering agent, and a drying agent.

4. A stencil sheet coated with the final-re action product of a mixture comprising a colloidal protein, a Vegetable drying oil, a tempering agent, and a metallic drying a ent,

5. A stencil sheet coated with the iinal-re; action product of a mixture comprising a invention is lelij particuits prc'terred "mbodnnent,

colloidal protein, a vegetable drying oil, a

tempering agent, and litharge.

6. A stencil sheet coated with a mixture comprising uncoagulated glue, linseed oil, a drying agent, and glycerinc.

7. A stencil sheet coated with a mixture comprising uncoagulated glue, linseed oil, glycerinc, and a metallic drying agent.

.8. A stencil sheet coated with a homogeneous mixture of uncoagulated glue, linseed oil, glycerine, and litharge. 9. A stencil coated with a mixture comprismg an uncoagulated colloidal protein, a vege table drying oil, a tempering agent, and a drying agent 10. A stencil sheet coated with a mixture of glue about 32 parts, linseed oil 12 parts, glycerine about 40 parts and litharge.

11. A stencil sheet carrying a coating ineluding an uncoagulated colloidal protein in admixture with a vegetable drying oil, and a tempering agent.

12. A stencil sheet carrying a. coating including an uucoagulated colloidal protein in admixture with linseed oil and a tempering agent.

13. A stencil sheet carrying a coating including llllCilllglllilti-ftl glue in admixture with a vegetable dryim oil, and a tempering agent.

i i. A stencil sheet carrying a coating including uncoagulated glue in admixture with linseed oil, and-a tempering agent.

15. A stencil sheet coated with a product including an uncoagulatcd protein colloid kept plastic by treatment with an organic softening agent in adn'iixture with a substantial portion of a vegetable drying oil of the group mx-n'mrising linseed oil, Cliinawood oil andsoya bean oil.

Signed at Chicago this 7th day of Septem ber, 1928.

PAUL a. GOLLNIOK. NAOMI GOLLNICK. 

